We are involved in a study of the genetic and/or epigenetic factors involved in the control of the expression of the malignant phenotype in human cells. This is accomplished by appropriate hybridizations between malignant and normal cells and assaying for tumorigenicity in immunosuppressed animals. Detailed chromosomal analyses will identify the specific chromosome(s) involved in the expression and suppression of malignancy. The role of epigenetic factors in the control of malignancy will be examined by enucleating cells which carry antibiotic resistant mitochondrial markers and fusing the anucleate cytoplasms with whole cells. Hybrids can then be isolated in the appropriate selective media. We are also involved in determining which transformed phenotypic markers are specifically associated with the malignant phenotype and whether they are under separate regulatory control. The techniques developed in this study will also be useful for the general areas of somatic cell genetics, cellular differentiation and development.